Die von Jens Timmermann besorgte Neuausgabe innerhalb der Philosophischen Bibliothek bietet den vollständigen Wortlaut der beiden Originalausgaben von 1781 und 1787. Der Kantische Text wurde unter Wahrung der Interpunktion und sprachlicher Eigenheiten sehr behutsam an die heutigen orthographischen Regeln angeglichen. Die semantisch bedeutenden Korrekturvorschläge späterer Herausgeber (nicht nur der Akademie-Ausgabe) sind, wo sie nicht in den Text Aufnahme gefunden haben, am Fuß der Seite verzeichnet. Alle wesentlichen Unterschiede zwischen den Originalausgaben sind durch Kursivdruck hervorgehoben, größere Abweichungen ganzer Textstücke - etwa (...) in der Einleitung und im Kapitel über Phaenomena und Noumena - wurden synoptisch gegenübergestellt, so daß Art und Umfang der Umarbeitung unmittelbar abgelesen werden können. Die durchgängig neu bearbeitete Studienausgabe folgt in den Grundprinzipien der seit 1926 in Forschung und Lehre maßgeblichen Ausgabe von Raymund Schmidt, die hiermit abgelöst wird. Sie wird ergänzt durch eine umfangreiche Bibliographie von Heiner Klemme sowie durch einen ausführlichen Personen- und Sachindex. (shrink)

It is discussed how the Weyl geometric generalization of Riemannian geometry relates to Jordan-Brans-Dicke theory and how it leads to a weak generalization of Einstein gravity. The generalization of geometry goes back to Weyl's proposal of 1918; the generalization of gravity was proposed by Omote, Utiyama, Dirac and others in the 1970s. Here we reconsider the conceptual potential of this approach for establishing links between gravity, the electroweak sector of elementary particle physics, and cosmology. We explore the possibility of unifying (...) the Higgs field of the standard model, imported to Weyl geometry, with a gravitational scalar field in a common Lagrangian probed at different energy levels. (shrink)

On the occasion of the recent experimental detection of a Higgs-type particle at the Large Hadron Collider at CERN, the paper reviews philosophical aspects of the Higgs mechanism as the presently preferred account of the generation of particle masses in the Standard Model of elementary particle physics and its most discussed extensions. The paper serves a twofold purpose: on the one hand, it offers an introduction to the Higgs mechanism and its most interesting philosophical aspects to readers not familiar with (...) it; on the other hand, it clarifies widespread misunderstandings related to the role of gauge symmetries and their breaking in it. (shrink)

This is a book that no one but Weyl could have written--and, indeed, no one has written anything quite like it since.

The paper investigates the spontaneous breaking of gauge symmetries in gauge theories from a philosophical angle, taking into account the fact that the notion of a spontaneously broken local gauge symmetry, though widely employed in textbook expositions of the Higgs mechanism, is not supported by our leading theoretical frameworks of gauge quantum theories. In the context of lattice gauge theory, the statement that local gauge symmetry cannot be spontaneously broken can even be made rigorous in the form of Elitzur’s theorem. (...) Nevertheless, gauge symmetry breaking does occur in gauge quantum field theories in the form of the breaking of remnant subgroups of the original local gauge group under which the theories typically remain invariant after gauge fixing. The paper discusses the relation between these instances of symmetry breaking and phase transitions and draws some more general conclusions for the philosophical interpretation of gauge symmetries and their breaking. (shrink)

"Symmetry" was one of the most important methodological themes in 20th-century physics and is probably going to play no lesser role in physics of the 21st century. As used today, there are a variety of interpretations of this term, which differ in meaning as well as their mathematical consequences. Symmetries of crystals, for example, generally express a different kind of invariance than gauge symmetries, though in specific situations the distinctions may become quite subtle. I will review some of the various (...) notions of "symmetry" and highlight some of their uses in specific examples taken from Pauli's scientific oevre. This paper is based on a talk given at the conference "Wolfgang Pauli's Philosophical Ideas and Contemporary Science", May 20.-25. 2007, at Monte Verita, Ascona, Switzerland. (shrink)

In der Debatte um den wissenschaftlichen Realismus gewinnt zunehmend der Strukturenrealismus - dessen Auffassung zufolge der Realgehalt wissenschaftlicher Theorien in deren mathematisch-logischer Struktur liegt - an Bedeutung. Die vorliegende Arbeit untersucht diese These anhand der in unserer fundamentalen Physik bedeutsamsten Klasse von Theorien, den Eichtheorien, die durch spezielle lokale Symmetriestrukturen gekennzeichnet sind. Die Arbeit bietet dem Leser in ihren ersten Kapiteln einen Einstieg in die zentralen Themen Symmetrien, wissenschaftlicher Realismus und Eichtheorien. In den im Mittelteil durchgeführten Analysen werden Quanten- und (...) Gravitations-Eichtheorien in konzeptioneller Hinsicht - vor allem bezüglich der zugrundeliegenden Prinzipien - und ontologischer Hinsicht - mit Blick auf die Unterbestimmtheit der Entitäten und verschiedener Lokalitätsannahmen - im Detail untersucht. Resultierend ergibt sich eine Stützung des Strukturenrealismus, jedoch nicht in dessen radikaler ontischer Variante, sondern in der moderateren epistemischen oder allenfalls intermediären Spielart, bei der sowohl Strukturen als auch deren Träger existieren, wobei letzterer jedoch amorph und und mithin epistemisch unverfügbar ist. (shrink)

Given its importance in modern physics, philosophers of science have paid surprisingly little attention to the subject of symmetries and invariances, and they have largely neglected the subtopic of symmetry breaking. I illustrate how the topic of laws and symmetries brings into fruitful interaction technical issues in physics and mathematics with both methodological issues in philosophy of science, such as the status of laws of physics, and metaphysical issues, such as the nature of objectivity.

This contributed volume is the result of a July 2010 workshop at the University of Wuppertal Interdisciplinary Centre for Science and Technology Studies which brought together world-wide experts from physics, philosophy and history, in order to address a set of questions first posed in the 1950s: How do we compare spacetime theories? How do we judge, objectively, which is the “best” theory? Is there even a unique answer to this question? -/- The goal of the workshop, and of this book, (...) is to contribute to the development of a meta-theory of spacetime theories. Such a meta-theory would reveal insights about specific spacetime theories by distilling their essential similarities and differences, deliver a framework for a class of theories that could be helpful as a blueprint to build other meta-theories, and provide a higher-level viewpoint for judging which theory most accurately describes nature. But rather than drawing a map in broad strokes, the focus is on particularly rich regions in the “space of spacetime theories.” -/- This work will be of interest to physicists, as well as philosophers and historians of science working with or interested in General Relativity and/or Space, Time and Gravitation more generally. (shrink)

The article proposes a novel approach to the much discussed question of which symmetries have ‘direct empirical significance’ and which do not. The approach is based on a development of a recently proposed framework by Hilary Greaves and David Wallace, who claim that, contrary to the standard folklore among philosophers of physics, ‘local’ symmetries may have direct empirical significance no less than ‘global’ ones. Partly vindicating the standard folklore, a result is derived here from a number of plausible assumptions, that (...) states that local symmetries can indeed have no direct empirical significance. Ways to interpret the result are considered and possible morals are outlined. 1 Introduction2 Greaves and Wallace on Interior versus Non-interior Symmetries3 Elaborating on the Greaves/Wallace Framework4 The Result5 Problems with ’t Hooft’s Beam Splitter6 Summary and Conclusion. (shrink)

The constrained Hamiltonian formalism is recommended as a means for getting a grip on the concepts of gauge and gauge transformation. This formalism makes it clear how the gauge concept is relevant to understanding Newtonian and classical relativistic theories as well as the theories of elementary particle physics; it provides an explication of the vague notions of “local” and “global” gauge transformations; it explains how and why a fibre bundle structure emerges for theories which do not wear their bundle structure (...) on their sleeves; it illuminates the connections of the gauge concept to issues of determinism and what counts as a genuine “observable”; and it calls attention to problems which arise in attempting to quantize gauge theories. Some of the limitations and problematic aspects of the formalism are also discussed. (shrink)

The world appears to be well described by gauge theories; why? I suggest that gauge is more than mathematical redundancy. Gauge-dependent quantities can not be predicted, but there is a sense in which they can be measured. They describe “handles” though which systems couple: they represent real relational structures to which the experimentalist has access in measurement by supplying one of the relata in the measurement procedure itself. This observation leads to a physical interpretation for the ubiquity of gauge: it (...) is a consequence of a relational structure of physical quantities. (shrink)